In vivo confocal microscopy was considered useful in the rapid diagnosis of AK. The Acanthamoeba cysts were observed almost exclusively in the epithelial cell layer as highly reflective, round or stellate, high-contrast particles with a diameter of 10 to 20 μm. It was suggested that invasion of Acanthamoeba cysts into Bowman's layer may be a useful predictor for a persistent clinical course. The trophozoites are pear-shaped or irregularly wedge-shaped structures, some surrounded by a brilliant halo some exhibiting fine pseudopodia-like extensions, with mean size of 30.2 µm (range 19.2-55.6μm). It was reported to present in cornea stroma. Highly reflective activated keratocytes forming a honeycomb pattern change was reported to be present around the keratoneuritis. In addition, infiltration of inflammatory cells, possibly polymorphonuclear cells, was observed along with the keratocytes in cases of AK. However, the in vivo confocal microscopic findings in patients with AK is still limited. Some clinical findings may not be correlated with the reports published before.